There is no easy way to study diseases of the brain. Extracting brain cells, or neurons, from a living patient is risky, while examining a patient's brain post-mortem only reveals the disease's final stages. And animal models, while incredibly informative, have fallen short during the crucial drug-development stage of research. But scientists have taken a potentially more powerful approach: An advanced stem-cell technique that creates a human model of degenerative disease in a dish.View full story